syzbot


KCSAN: data-race in dont_mount / lookup_fast

Status: moderation: reported syz repro on 2023/12/08 00:01
Subsystems: exfat
[Documentation on labels]
Reported-by: syzbot+66941b35e83b90763e23@syzkaller.appspotmail.com
First crash: 1419d, last: 1d00h
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
edadd30d-b884-42c4-9ca4-785581c5ff50 assessment-kcsan Benign: ✅  Confident: ✅  KCSAN: data-race in dont_mount / lookup_fast 2026/02/25 02:23 2026/02/25 02:23 2026/02/25 02:33 305c0ec5cd886e2d13738e28e1b2df9b0ec20fc9
644e3073-a037-46b9-86ba-bbb6332d8275 assessment-kcsan 💥 KCSAN: data-race in dont_mount / lookup_fast 2026/01/15 13:55 2026/01/15 13:55 2026/01/15 13:59 a9d6a79219801d2130df3b1a792c57f0e5428e9f failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "128" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/build/ae22ff18a2bdd936aac7c711f799309c8ad3d8de" "bzImage" "compile_commands.json"]: exit status 2
Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/12/16 03:07 38m retest repro upstream report log

Sample crash report:
==================================================================
BUG: KCSAN: data-race in dont_mount / lookup_fast

read-write to 0xffff888106ae8f00 of 4 bytes by task 3530 on cpu 0:
 dont_mount+0x27/0x40 include/linux/dcache.h:363
 vfs_unlink+0x298/0x430 fs/namei.c:4345
 do_unlinkat+0x236/0x4c0 fs/namei.c:4407
 __do_sys_unlink fs/namei.c:4455 [inline]
 __se_sys_unlink fs/namei.c:4453 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4453
 x64_sys_call+0x28a3/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106ae8f00 of 4 bytes by task 2784 on cpu 1:
 d_revalidate fs/namei.c:860 [inline]
 lookup_fast+0xd9/0x2a0 fs/namei.c:1641
 walk_component+0x3f/0x230 fs/namei.c:2000
 lookup_last fs/namei.c:2469 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2493
 filename_lookup+0x127/0x300 fs/namei.c:2522
 user_path_at_empty+0x42/0x120 fs/namei.c:2929
 do_readlinkat+0x92/0x210 fs/stat.c:499
 __do_sys_readlink fs/stat.c:532 [inline]
 __se_sys_readlink fs/stat.c:529 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:529
 x64_sys_call+0x264b/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00600008 -> 0x00008008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2784 Comm: udevd Not tainted 6.10.0-rc2-syzkaller-00222-gd30d0e49da71 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================

Crashes (972):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/06 22:07 upstream d30d0e49da71 121701b6 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/02/27 10:55 upstream 3f4a08e64442 a2f13f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/02/22 01:39 upstream fa5c82f4d2bb 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/02/14 22:12 upstream 3e48a11675c5 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/02/14 14:53 upstream 770aaedb461a 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/02/10 14:00 upstream 72c395024dac 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/01/19 16:08 upstream 24d479d26b25 a9fc5226 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/01/13 21:49 upstream b54345928fa1 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/01/05 17:00 upstream 3609fa95fb0f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2026/01/03 18:03 upstream 805f9a061372 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/12/28 11:21 upstream d26143bb38e2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/12/27 10:47 upstream c53f467229a7 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/12/19 15:17 upstream dd9b004b7ff3 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/12/01 22:50 upstream 1d18101a644e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/12/01 06:54 upstream 7d0a66e4bb90 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/28 03:02 upstream e1afacb68573 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/26 22:29 upstream 4941a17751c9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/21 18:59 upstream fd95357fd8c6 4fb8ef37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/20 17:48 upstream 8e621c9a3375 2cc4c24a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/18 18:13 upstream 5bebe8de1926 ef766cd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/17 12:00 upstream 6a23ae0a96a6 ef766cd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/16 19:04 upstream 7254a2b52279 f7988ea4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/15 22:01 upstream f824272b6e3f f7988ea4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/14 20:29 upstream d4f8cccc6230 f7988ea4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/14 13:20 upstream 6da43bbeb691 f7988ea4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/13 03:08 upstream e927c520e1ba 07e030de .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/11 09:22 upstream 4427259cc7f7 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/10 19:56 upstream 4ea7c1717f3f 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/10 02:25 upstream e9a6fb0bcdd7 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/09 14:18 upstream 439fc29dfd3b 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/08 10:22 upstream e811c33b1f13 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/06 16:44 upstream dc77806cf3b4 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/05 20:03 upstream 1c353dc8d962 a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/05 06:31 upstream 17d85f33a83b a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/05 04:44 upstream 17d85f33a83b 686bf657 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/02 20:43 upstream 6146a0f1dfae 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/11/01 22:05 upstream 691d401c7e0e 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/10/31 17:02 upstream 58fdd8484c05 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/10/31 05:20 upstream d127176862a9 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/10/28 01:56 upstream fd57572253bc fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/10/27 12:26 upstream dcb6fa37fd7b fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/10/26 17:30 upstream dbfc6422a34d c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/10/22 03:07 upstream 552c50713f27 252fbbad .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2025/10/21 07:01 upstream 6548d364a3e8 9832ed61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2023/12/07 23:38 upstream 9ace34a8e446 28b24332 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2023/12/04 22:29 upstream bee0e7762ad2 f819d6f7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
2022/04/10 15:50 upstream 1862a69c9174 e22c3da3 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in dont_mount / lookup_fast
* Struck through repros no longer work on HEAD.